Choose the heat-pump noise assessment route before commissioning work
A heat pump noise brief should start with the installation and its planning route. The 2026 IOA/CIEH professional advice note sets out proportionate options for domestic installations where permitted development rights do not apply.
Start by checking the planning position for the relevant UK nation and site. An acoustic calculation alone does not establish permitted development rights. Also distinguish a domestic installation from a commercial or more complex plant proposal.
The following route prompts help you prepare a discussion with the installer, planning adviser and acoustician. They do not determine permission or provide a noise calculation.
Heat pump noise: three routes in the 2026 note
| Starting point | Route to discuss |
|---|---|
| Permitted development is unavailable for a non-acoustic reason | PDR+: installer-led MCS 020a calculation, where no greater caution is needed. |
| PDR+ indicates a minor exceedance | Level 1: a suitably qualified acoustician considers sound propagation and the note’s 37 dB(A) criterion. |
| Exceptional or sensitive circumstances | Level 2: a suitably qualified acoustician assesses the detailed context, including relevant cumulative effects. |
For Level 1, the note uses 37 dB(A) incident sound pressure level, assessed one metre from the centre of a habitable-room window or door. Exclude the reflection from that assessment façade. It is not a universal boundary limit or the manufacturer’s sound power rating. Confirm the method and local requirements with the responsible assessor.
For help selecting a project scope, see ACP’s heat-pump noise assessment service.
Prepare the heat pump noise data request
Send the exact proposed model and its supporting data, not a sales description for a product range. Also keep the original data sheet with its date and version. Then ask the supplier to identify the operating conditions behind each value.
| Record | Practical request |
|---|---|
| Equipment identity | Manufacturer, complete model reference, number of units and relevant accessories. |
| Sound data | Sound power information, its test conditions and available maximum operating data. Label any quiet-mode value clearly; do not use it as a substitute for the route’s specified data. |
| Design operation | Heating and hot-water assumptions, relevant cooling operation and how controls will operate. |
| Location | A scaled layout, elevations, mounting position, distances, nearby windows and proposed screens. |
| Installation constraints | Manufacturer clearances, airflow needs, maintenance access, mounting and pipework arrangements. |
| Decision record | Who supplied each item, who accepted it for assessment and what still needs confirmation. |
In addition, the note distinguishes the data used for different routes. For Level 1 it calls for maximum sound power where available, otherwise a 5 dB adjustment to the energy-label value. Therefore, let the acoustician select and justify the input. Do not substitute a quieter marketing figure.
Resolve the location while options remain
Discuss siting before the landscape or servicing layout is fixed. The project team should understand which nearby rooms, spaces and other equipment the assessor needs to consider. Also make uncertainty visible on the plan.
If a screen or enclosure is proposed, ask the acoustic and building-services designers to review the same detail. A measure that changes airflow or access needs coordinated review. Then record how the installer will deliver the accepted design.
Illustrative example: a unit moves from a side passage to a courtyard after the calculation. Send the revised layout and equipment information back for review. Do not carry the earlier conclusion into the application simply because the model number has stayed the same.
Make the assessment useful at installation and handover
Finally, keep the accepted equipment, drawing revision and operational assumptions with the installation brief. Also name the person who will refer substitutions back to the assessor. Then check that the final information describes what the contractor will install.
Our plant acoustic assessment briefing guide explains the wider information handover. To discuss an uncertain route or evidence gap, send ACP the site, proposal and available equipment information.
Source and scope
Primary source: IOA and CIEH, Domestic Air Source Heat Pumps: Professional Advice Note (2026), including its four-page guidance and annex. This is professional advice, not a new planning permission or a UK-wide permitted-development rule. The briefing tables are ACP coordination aids.